OK. So I did a search and read the M4 Feedramp discussion under the Important Threads and Info. Sticky but I still don't understand exactly what the best feed ramp option is. I am getting ready to purchase my first upper from CMMG (I have owned 2 ar15s before that were stock but never pieced one together myself). They have three choices under Feed Ramp Option: 1) Anodized; 2)No Ramps; 3)Extended/Polished Ramps (an extra 10 bucks for this option).

I was wondering if someone could give me a simple explanation of these different types of Feed Ramps. I am going for total reliability in this particular build (a tacticool carbine). This is the last thing I need to understand before ordering my new upper.

The barrel extension (the usually black part on the back of the barrel) on an M4 barrel are cut a little deeper than on the standard rifle barrel.

The upper receiver on an M4 has two small cuts under the barrel socket that provide additional clearance for rounds in the magazine to feed into the barrel extension.

Regardless of what you hear to the contrary, it helps feed hollow point (match) ammo better and gives older, worn magazines a longer life.

I have found the ramps to be helpful in both M4s and AKs, when hollow point (match) ammo is used.

I would opt for the anodized M4 ramps, if you have a choice, on the upper receiver, provided you use a barrel with M4 ramps.

If you use a barrel with standard rifle feed ramps (no ramps), I recommend you do not use an M4 cut upper.

The Constitution is over 200 years old and societies change. It has to change with society, like a living organism, or it will become brittle and break. But you would have to be an idiot to believe that." —Justice Antonin Scalia

"Extended and Polished" is what is commonly known as "dremel ramps" and is the method that RRA uses. What they do is use a standard upper and standard barrel extension and then use a dremel tool to lengthen the feed ramps. This helps some guns but leaves the aluminum un-anodized and more importantly it doesn't give you the ability to switch barrels without re-doing the ramps. If you use the correct M4 barrel extension with the M4 upper you can switch barrels with other M4 ramped barrels without having to mess with this.I can't speak for CMMG but I believe they initially used the dremel ramp method on all their uppers and are now in the process of converting over to the correct (IMO anyway) method. I just bought an upper from CMMG with the anodized ramps. CMMG is a great outfit to deal with. I personally would get the anodized M4 ramps with any gun I buy.